Question
A sum of ₹12,000 is invested for 3 years at a certain
rate of simple interest. If the same sum was invested at the same rate for 2 years under compound interest (compounded annually), it would earn ₹240 more. Find the rate of interest per annum.Solution
Let the rate of interest be R%. Simple interest for 3 years = (12,000 × R × 3) ÷ 100 = 360R Compound interest for 2 years = 12,000 × [(1 + R/100)^2 - 1] The difference is ₹240: 12,000 × [(1 + R/100)^2 - 1] - 360R = ₹240 Simplify and solve for R. Approximating, R ≈ 10%. Correct Option: d
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